The present invention relates to a control system and method for the operation of a clothes dryer.
It is well known to provide clothes dryers with a lint filter to remove lint picked up from the articles or load being dried. If the filter becomes clogged by excessive lint, the airflow through the dryer is restricted and the necessary time to dry the load is increased.
The status of the lint filter may be monitored by means of airflow and pressure sensors that provide indication of blockage during the time air is flowing through the dryer. Typically, serious blockages of airflow result in excessive temperatures in the area of the air heater, resulting in the intermittent opening of a high limit thermostat that deactivates the heater. The sensors or thermostats can be connected to an indicator to apprise the operator of the condition. However, these methods provide an indication of air blockage only during airflow through the dryer.
It is desirable to know the degree of dryness of the load. This is useful for operator removal of the load at a given dryness or for helping the operator predict the time remaining to dry.
The dryness of the load may be monitored by such means as sensing the rapid rise in exhaust temperature when the load is nearly dry and by actual humidity sensors. Unfortunately, the monitoring of exhaust temperature does not provide entirely satisfactory results and humidity sensors represent a substantial increase in sensor costs.